Methods for supplying cryptographic algorithm constants to a storage-constrained target
View Patent ↗The present invention provides for authenticating a message. A security function is performed upon the message. The message is sent to a target. The output of the security function is sent to the target. At least one publicly known constant is sent to the target. The received message is authenticated as a function of at least a shared key, the received publicly known constants, the security function, the received message, and the output of the security function. If the output of the security function received by the target is the same as the output generated as a function of at least the received message, the received publicly known constants, the security function, and the shared key, neither the message nor the constants have been altered.
1. A method for authenticating a message, comprising:
performing a security function upon the message to generate a message authentication code, wherein the security function utilizes at least one publicly known constant to perform the security function upon the message, and wherein the at least one publicly known constant is selected from a set of publicly known constants used to implement the security function;
sending the message to a receiver;
sending the message authentication code to the receiver; and
sending the at least one publicly known constant, used by the security function to perform the security function upon the message, to the receiver, wherein the receiver authenticates the message based on the message authentication code and the at least one publicly known constant.
2. The method of claim 1 , wherein the security function comprises a hash function.
3. The method of claim 1 , wherein the authentication comprises a determination that the message is at least one of authentic or not authentic.
4. The method of claim 1 , wherein the security function further comprises at least one of an encryption function or a decryption function.
5. The method of claim 1 , wherein the security function is a Secure Hash Algorithm (SHA), and wherein the set of publicly known constants comprises the first 64 bits of the fractional parts of the cube roots of the first eighty prime numbers.
6. The method of claim 1 , wherein the receiver does not store the set of publicly known constants.
7. The method of claim 1 , further comprising:
authenticating, at the receiver, the message as a function of at least a shared key, the at least one publicly known constant, the security function, the message, and the message authentication code.
8. The method of claim 2 , wherein the hash function is applied to a secret key, the at least one publicly known constant, and the message such that the resulting message authentication code is equal to a hash of the combination of the secret key, the at least one publicly known constant, and the message.